At the present time there is no safe, simple, efficient and low cost method for controlling the motions and positions of multiple elevator cabs that move independently of each other in the same elevator shaft.
Most current elevator control systems which control multiple cabs in the same shaft, only operate with one elevator cab in each separate region of each elevator shaft, so it is physically impossible for two cabs to collide. Some of these systems express cabs from the ground floor to groups of upper floors and then operate just one cab in each group of floors. All of these systems are very inefficient because each region of each elevator shaft is only being used by one elevator cab. Other high tech control systems propose that multiple cabs can be operated independently of each other in each elevator shaft where sensors attempt to prevent collisions by sensing the speed of each cab and their distances apart, so that a computer can attempt to adjust the speed and distance of each moving cab in the same elevator shaft. However, most of these systems are very complicated, unreliable, expensive and unsafe, because many unexpected things can happen to cause collisions, such as power losses, power fluctuations, data cross feeds, a sensor can fail, there can be an electrical cross circuit, computers can crash, and so forth. A few systems have mechanical collision prevention methods, but they too can fail, and they are clumsy, require slow elevator speeds, and are limited to two elevator cabs.
While it is true that all elevator systems can be exposed to earthquakes, hurricanes, tornadoes, lightning, floods, fires, sabotage, terrorism, low flying airplanes or the like, these possible extraordinary occurrences should not be attributed to an otherwise fail safe computer control system or its method of operation. Accordingly, there is a need for a simple, efficient, low cost and a failsafe computer control system and method thereof which solves all the problems as discussed above.